Tarzan is a pulp hero, which are forerunners to superheroes (like the Shadow and Doc Savage). He's not commonly counted as a superhero, but then some people don't count Batman as a superhero either. My own definition of a superhero is simply a character based on Superman.

I understand your point, but consider this origin......

A baby is orphanned by the death of his parents. He is found, adopted, and raised by parents who are not of his kind in a world alien to his birthright. His given name is unknown to his new parents and they give him a new name and identity.As he matures he develops abilities that place him above the capabilities of normal men.